Monitors for hydrogen sulfide, an invisible gas found in some oil reserves, were not working when Jacob Dean responded to an alarm to check a pump. Dean was exposed to fatal levels of the gas.

Five months after a hydrogen sulfide leak at the Pemex Deer Park refinery killed two contract workers, the U.S. Chemical Safety Board said they both died while trying to flee the scene.

Purified Na₂S was synthesized from barium sulfide through controlled chemical ... including X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (TOF-SIMS ...